The final disposal of Germany's highly radioactive waste is to take place in a mine that is to be excavated for this purpose at a depth of between 300 and 1,500 metres. In addition to the geological barrier, this repository should also have technical and geotechnical barriers (multi-barrier system) and thus provide the best possible protection of the biosphere from the ionizing radiation emitted by the waste for a period of one million years. The Site Selection Act, which sets the framework for the search for a repository for high-level radioactive waste, names claystone as one of three possible host rocks for a repository.
Clay minerals and the soils, clays and mudstones represent a valuable resource on the one hand, while on the other hand they are often used as geological barriers. The Federal Institute for Geosciences and Natural Resources (BGR) is therefore working intensively with these geo-materials and their potential applications, with a substantial proportion of these activities in the areas of research & development (R&D) and consulting & services (B&D) relating to the final disposal of highly radioactive waste. Clays and mudstones have favourable barrier properties due to their generally low permeability or rather rock permeability. The plasticity is typical for some of them, as well as their chemical buffering effect and retention capacity for radionuclides.
BGR's activities in the field of repository research are dedicated to sites where radioactive waste is already present or could be disposed in the future. In addition, through its involvement in international collaborations (e.g. Meuse/Haute-Marne rock laboratories at the Bure site and Mont Terri in Switzerland), BGR contributes to a fundamental understanding of claystones potentially suitable as host rocks and the various barriers of a repository system. The gained knowledge will be made available to the public through overview studies as well as in technical reports and through the publication of peer-reviewed articles in scientific journals.
In order to identify emerging issues and topics, BGR scientists exchange regularly information with the international and national expert community on the state of the art in science and technology with regard to the final disposal of high-level radioactive waste and the German site selection process. Through its cross-scale research activities, BGR contributes to a better understanding of the host rock claystone and thus supports the search for a site for high-level radioactive waste in Germany.